1. Field
Example embodiments generally relate to jet pump sensing line support clamp assemblies usable in nuclear reactors for jet pump sensing line component repair and replacement. Additionally, example embodiments relate to method of using jet pump sensing line repair apparatuses in a Boiling Water Reactor (BWR).
2. Description of Related Art
Generally, BWRs include jet pumps as part of a recirculation system to effectively move coolant and moderator through a nuclear core. In order to evaluate operating conditions within the nuclear core, it may be desirable to monitor the flow rate through the core, including flow rate of coolant from the jet pumps. Typically, a jet pump sensing line is used to measure flow rate from the jet pumps by measuring a pressure differential between the inlet and nozzle of the jet pumps.
FIGS. 1 and 2 are illustrations of a related art jet pump sensing lines 100 coupled to a lower diffuser shell 110 at the base of the jet pumps by a sensing line support 120 welded to both the diffuser shell 110 and the jet pump sensing lines 100. The sensing lines 100 are typically welded to the support 120 in support grooves 125, and, as such, are subject to flow-induced vibration in the jet pump.
The jet pump sensing lines 100 shown in FIGS. 1 and 2 are typically installed within a BWR core and are accessible only during scheduled plant outages for refueling and repair. These outages occur at several month intervals, and thus components within the core, including the jet pumps and jet pump sensing lines 100, must operate for lengthy periods before they can be inspected or repaired.
Further, BWR core operating conditions include high levels of radioactivity due to fission occurring in the fuel rods. Radioactivity, particularly neutron flux commonly encountered in operating nuclear cores, degrades many materials' strength and elasticity over time. Components within the core, including jet pump sensing lines 100 and sensing line supports 120, are subject to premature brittling and cracking due to radiation exposure.
The combination of flow-induced vibration, lengthy operating cycles, and radiation degrading may cause jet pump sensing line welds to fail, allowing the jet pump sensing lines 100 to become unseated from their support 120 and become damaged and/or damage other core components. Related art repair means typically include re-welding broken supports during plant outages.